In recent years, particularly in industrial fields such as manufacturing and transportation, improvement of the work environment on production floors can be important. For example, standards for allowable levels of noise and vibration are becoming more severe. Further, noise in residential environments may be troublesome for neighbors, and quieter performance may also be desirable for home electrical appliances and machinery products.
Vibrations can be easily transmitted in equipment that includes metal materials. Metal panels can often be a source of noise. Therefore, countermeasures for preventing or reducing vibration and noise can be desirable.
Conventional vibration-deadening materials which may be used for preventing noise and vibration can include, e.g., composite materials having a multilayer structure which includes metal layers surrounding an intermediate layer made of a viscoelastic resin composition. Such material can convert vibrational energy to heat energy, e.g., by slip deformation of the intermediate viscoelastic resin layer which may occur during vibrational bending of the material, which may attenuate the vibration rate and amplitude, and thereby reduce sound propagation. Such composite material can provide better vibration-deadening performance, e.g., when it is in direct contact with a vibration source or when used as a cover or other part of a vibration source.
Such composite vibration-deadening materials may be used, for example, in automobile oil pans, engine head covers, engine room shield plates, dash panels, floor panels, gear covers, chain covers, muffler covers, mufflers, floor housings, and other parts of automobiles, motorcycles, farm machinery, motor covers, compressor covers, evaporator covers and other parts of freezing temperature adjustment equipment, computer cases, hard disk drive cases, speaker frames and other parts of acoustic electronic equipment, chain saw covers, generator covers, lawn mower covers and other parts of outdoor equipment, steps, doors, flooring, roofing, and other construction materials, and other applications.
Metal materials which may be used, for example, in household electrical products and automobiles, can be treated with chromate treatment. Such chromate treatment can be inexpensive and may provide excellent corrosion resistance, and may be widely used as a paint undercoat and/or for temporary rust prevention. However, in view of concerns about the global environment, use of environmental loading substances (e.g., lead, hexavalent chromium, cadmium, mercury, etc.) has been subject to increasingly strict regulation in recent years.
To improve bondability between the metal sheet and the intermediate viscoelastic resin layer in a conventional composite vibration-deadening material, a chromate treatment can be applied as an undercoat treatment of the metal sheet bonding surface. However, a composite vibration-deadening material which can be made without using chromate may be preferable, e.g., for environmental reasons.
Various studies have been performed to find techniques to replace chromate when surface treating steel sheet. For example, Japanese Patent Publication (Kokai) No. 04-48081 describes a method of surface treatment using a transition metal-based (e.g., from the VIA group) aqueous ammonium molybdate solution which may have a passivation performance similar to that of chromic acid.
Further, Japanese Unexamined Patent Publication (Kokai) No. 2003-55777 describes a chromate-free treated hot dip zinc-aluminum alloy plated steel sheet having a coat containing a zirconium compound and a vanadic compound. Japanese Unexamined Patent Publication (Kokai) No. 2001-89868 describes an example of a non-chromate chemical treatment containing a tannic acid, a silane coupling agent, and silica particles.
Many conventional viscoelastic resins or viscoelastic resin compositions can be used in an intermediate layer of a composite vibration-deadening material. Such resins or resin compositions can include, for example, a polyester resin (as described, e.g., in Japanese Unexamined Patent Publication (Kokai) No. 50-143880) a resin composition which may include a polyester resin and a plasticizer (as described, e.g., in Japanese Unexamined Patent Publication (Kokai) No. 52-93770), a resin compositions obtained by combining a plurality of polyester resins as described, e.g., in Japanese Unexamined Patent Publication (Kokai) No. 62-295949 and Japanese Unexamined Patent Publication (Kokai) No. 63-202446), a polyurethane resin foam (as described, e.g., in Japanese Unexamined Patent Publication (Kokai) No. 51-91981), a polyamide resin (as described, e.g., in Japanese Unexamined Patent Publication (Kokai) No. 56-159160), an ethylene-vinyl acetate copolymer (as described, e.g., in Japanese Unexamined Patent Publication (Kokai) No. 57-34949), an isocyanate prepolymer and vinyl monomer copolymer (as described, e.g., in Japanese Unexamined Patent Publication (Kokai) No. 55-27975), or a polyvinyl acetal resin as described, e.g., in Japanese Unexamined Patent Publication (Kokai) No. 60-88149), etc.
Cross-linking agents may be used, for example, in a viscoelastic resin composition containing a specific amorphous block copolymerizable polyester resin which may include a high glass transition temperature segment and a low glass transition temperature segment such as a lactone component (as described, e.g., in Japanese Unexamined Patent Publication (Kokai) No. 01-198622), a viscoelastic resin composition containing a polyester resin synthesized using a glycol having a dimer acid or a hydrogenated dimer acid and a side chain as a starting material (as described, e.g., in Japanese Unexamined Patent Publication (Kokai) No. 06-329770), a viscoelastic resin composition containing a copolymerizable polyester resin having an aromatic ring in the side chain (as described, e.g., in Japanese Unexamined Patent Publication (Kokai) No. 06-329771), a viscoelastic resin composition containing a copolymerizable polyester resin having a side chain containing five or more carbon atoms (as described, e.g., in Japanese Unexamined Patent Publication (Kokai) No. 07-179735), and so on.
Chromate-free treatment may be used for surface treated steel sheets. However, it may be desirable to provide a chromate-free bonding undercoat treatment which can generate a bondability equivalent to that obtained using a chromate treatment, particularly a durable bondability, for a composite vibration-deadening material.
For example, viscoelastic resin compositions such as those described in Japanese Unexamined Patent Publication (Kokai) No. 01-198622, Japanese Unexamined Patent Publication (Kokai) No. 06-329770, Japanese Unexamined Patent Publication (Kokai) No. 06-329771, and Japanese Unexamined Patent Publication (Kokai) No. 07-179735, can be based on thermosetting polyester-based resins and may create hydrogen bonds with a chromic acid hydrate of a chromate treatment applied to the surface of the metal sheet to generate a high bonding strength. A conventional chromate-free treatment, however, may not provide a bonding strength as good as that of a chromate treatment.
Thus, there may be a need for improved systems, methods, software arrangements and computer-accessible media for press-forming of materials which overcome the above-mentioned deficiencies.